Sound reproducer



Dec. 3, 1940. Q 1, PRICE 2,223,496

SOUND REPRODUCER Original Filed-Nov. 12, 1937- 2.Sheets-Sheet 1 I J22 vez22f02- 0s Zorn e Z Price,

14 ZarQzq V O. l. PRICE Dec. 3, 1940.

.222 e 22 2501' Us 50172 e. Z

Patented Dec. 3, 1940 UNITED STATES SOUND REPRODUCER Osborne I. Price, Frederick, Md.

Original application November 12, 1937, Serial No. 174,241, now Patent No. 2,180,482, dated November 21, 1989. Divided and this application August 16,1939, SerialZNo. 290,485

2 Claims.

My invention relates broadly to electrical sound reproducersand more particularly to an improved construction of electrical sound reproducer.

Thisapplication is a division of my application Serial No. 174,241, filed November 12, 1937, for Sound reproducer and method of manufacturing the same, now Patent 2,180,482, granted Nov. 21, 1939.

One of the objects of my invention is to provide-a construction of electrical sound reproducer of the magnetic type having a permanent magnetic field of extremely high flux density.

Another object of my invention is to provid a construction of permanent magnet type of electrical sound reproducer wherein a permanent magnetic field of extremely high flux density. is maintained continuously across an annularmagnetic gap in which a winding carried by a sound reproducing diaphragm is traversed by varying currents and wherein the high flux density is confined to the magnetic path of the sound reproducer per se and substantially shielded against external leakage. V

A further object of my invention is to provide a construction of electrical sound reproducer embodying a permanent magnet of toroidal shape terminating-man annular head and coacting with a. surrounding magnetic-plate providing an an- .nular gap in which a winding carriedby a sound reproducing diaphragmand traversed by varying currents is arranged to operate.

A still further object of my invention is .t provide a construction of sound reproducer whose characteristics remain substantially constant in dependently of wide variations in conditions of temperature and humidity while reproducing sound over a wide frequency response characteristic.

Other and further objects of my invention reside in the improved construction of electrical sound reproducer as set forth more fully in the specification hereinafter following by reference to the accompanying drawings in which:

Figure 1 is a vertical sectional view through an electrical sound reproducer constructed in accordance with my invention; Fig. 2 is afragmentary plan view of the permanent magnet employed in the electrical sound reproducerof my invention; Fig. 3 is a side elevation partially broken away and shown in. cross section of the permanent magnet employed in the electrical sound reproducer of my invention; Fig. 4 is a fragmentary view .of a modified form of permanent magnet which may be employed in the sound reproducer .of my inventiomthe view being partially broken away and shown in crosssection; Fig. 5 is a transverse sectional view through the electrical sound reproducer taken on line 5-5 of Fig. 1; Fig. 6 is a transverse sectional view through the electrical sound reproducer taken on line 66 of Fig. 25 .1; and Fig. 7 is a top plan view of the electrical sound reproducer with partsbroken away and illustrated in cross section.

My inventionis directed to an electrical sound reproducer capable of functioning under conditions encountered in marine and aircraft operation where the electrical sound reproducer is subjected to wide changes in temperature, barometric pressure and humidity conditions. I have successfully operated the electrical sound reproducer .ofmy invention on shipboard and in aircraft. 1 have devised a magnetic structure of electrical soundreproducer of my invention with a view of obtaining a permanent magnetic field of extremely high flux density. 1 provide a toroidal shaped permanent magnet formed from an alloy of aluminum, nickel and cobalt. The toroidal shaped permanent magnet is magnetized under conditions of high charging current and provides a flux density in the sound reproducer in a range 25 of 10,800 gausses or higher. I dispose the toroidal shaped permanent magnet in a path of soft steel which includes an annular gap within which the winding, supported by the sound reproducing diaphragm and carrying current variations is..disposed. I surround the magnetic system with a shield which is so complete that there is substantially negligible magnetic leakage from the magnetic structure. Moreover, the shield is so' constructed that the magnetic parts and the diaphragm are substantially protected against dempness, salt water, acid fumes, high pressures and vacuums, whereby the magnetic system and diaphragm operate independently of wide variations in conditions of temperature, barometric pressure and humidity.

Referring to thedrawings in detail, reference character I indicates the toroidal shaped permanent magnet employed in the electrical sound reproducer of my invention. The permanent magnet employed is formed from an alloy of aluminum, nickel and cobalt and when magnetized under control of a high charging current, a permanent magnetic field of the order of 10,800 gausses is established. The permanent magnet I tapers from a relatively large diameter adjacent its base ,to a smaller diameter adjacent the top thereof.

In Fig. 3 I have shown the permanent magnet with a straight wall, tapered so thatthe toroidal ,shapedpermanent magnet is substantially frustoconical. In Fig. 4 I have shown the permanent magnet having a gradual taper IA from a position adjacent the base to a position adjacent the top of the magnet. The permanent magnet I has a central bore extending longitudinally therethrough with diametrically opposite longitudinally extending grooves ISA and IBA for accommodating non-magnetic securing bolts I6 and I8 which pass through the soft steel base 4 and enter the soft steel cap plate 2. The soft steel cap plate 2 has a shaped annular head 2A and an angularly inclined wall 23 connected with head 2A through a curved interconnecting wall portion 20. The head 2A of the annular cap 2 is aligned with the annular face 3A of soft steel plate 3 The soft steel plate 3 is secured in position with respect to the soft steel base 4 with the cylindrical soft steel case 5 serving as a spacer member soft steel plate 3, the soft steel case 5 and through the soft steel base 4, returning to the permanent magnet.

The sound reproducing diaphragm is indicated generallyat 6 having. a central sound reproducing portion 6A and winding supporting portion 63 where the winding supporting portion 63 extends through the annular gap 35 for supporting winding 1 between soft steel annular head 2 and soft steel annular face 3A. The diaphragm is suspended by the annular flexible and resilient metallic rim I4 which is secured between flexible gaskets II and I2 by screw members 22, 23, 24 and 25 shown more clearly in Fig. 7. The screw members 22, 23, 24 and 25 pass into the annular plate 8 which forms part of the support. for the sound reproducing horn adapted to be connected to the screw threaded cylindrical neck 8A. The plate 8 has an annular recess 8B thereinwhich enables the plate 8 to completely cover the gaskets. H and I2 and form a tight seal against the entry of moisture, saltwater, acid fumes or gases. Plate 8' seats directly against the top l3 of the case. The top l3 may be of aluminum, zinc, brass or other non-magnetic material, and is provided with a central recess indicated .at I3A which aligns with the recess 8B in plate 8 allowing a snug fit for gasket l2 when the assembly is inserted in. position, thus further presenting an obstructive path against the entry of moisture, saltwater, acidpfumes, or gases. Top plate 13 also provides a connection means over which the top edge HA ofwthe non-'magnfltic {protective case I1 is rolled. The case I! is formed from aluminum or other suitable-non-magnetic material'and entirely -encases the magnetic parts .of the; sound reproducing;system. ,When rolled over at the-top edge ITA; a tight joint is pro,- vided ,Withrespect to topplatel3. The supporting plate 8 which carries the diaphragmassem'bly "and supports the sound reproducing horn may also be constructed from aluminum or bronze o'r other non-magnetic materials so that a com'plete non-magnetic housing is provided around the magnetic systemi Not onlyl'does' this non-magn etichousing aid in .confining the magnetic linesv l i ames a formed from aluminum, I have found that in certain instances that it is desirable to form the plate 8 from soft steel for the purpose of providing a magneticleakage path for avoiding 15 stray fleldswhere a bronze or aluminum plate would. allow .the passage of such leakage fields.

I provide-a cylindrical collar 9 within the screw threadedterminus 8A and a protective screen I0 within the cylindrical terminus for the protection of the sound reproducing diaphragm 6. 1

The plate 8'carries binding posts .3l and 32 in insulated position thereon as shown more par ticularly in Fig. .7. Binding. posts 3| and 32 are connected through leads- 29 and 30 to opposite 25 ends of winding 1- carried bythe coil'supporting portion 6B of the sound reproducing diaphragm. The plate 8 is removably secured in position as a complete: assembly in itself readily separable from the permanent magnetsystem by means of '30 screws 26,21, 28, and 33which pass through plate 8 an'denter the soft steel plate 3 through non-magnetic .plate 13 as indicated more particularly -in.Fig...7.. Whenplate8 is formed from softsteel ,for the purpose of. providing a magnetic leakagepath, the screws .26, 21,: 28.and 33 further. serve .as .a connectionto the soft steel plate. 3 through which .magnetic lines of force thread; 1? r l a As heretofore observed the complete soundre- 4 producing diaphragm assembly is supported by plate 8 which when secured imposition on the casing insures that the coil 1 maybe centered in the gap 35 between annular head 2A and annular magnetic. face 3A. The "Winding 1 is com 4 nected in the variable current circuit and 'when energized by variable currentscoacts with the intense magnetic field'est'ablished across-gap 35 for imparting vibrations. to the sound reproducing diaphragm 6 which is free to vibrate through flexible suspension l4, for .Tthe reproducing of sound. f: I a

The .loud speaker of my invention operates to reproduce sound uniformly overa widefrql ency that .all. parts. of the; structure: are prot'e'cted againstJvariations in....temperature; barometric pressure, and humidity, insures permanency in operation of. the fstructure whether in aircraft,' on? shipboard..zorxsunderother .6 severe conditions. Theifact that the parts fof the sound reproducer are constructed from' materials nbt subject to change under; conditioiifs' of wide variations iii temperat re;barometncgpressiire arid humidity further insures-"the permanency 'in F peratio i of the soundrprOducer.-- -While-I'Qhavedes'c be iny of- 'itspreiferredi e bodime i desirethat' it be s e mahat. ifi e imasibsmadeiand that"no limitations" upb my inventi ongare 7O tended-other tha n ma ows ters Pa near the U i A M of the-electrodynamic l Mashhad: transact type employing a permanent magnet field structure, in combination, magnetic means for providing an annular gap having a high flux density, an annular plate member of non-magnetic material disposed on said magnetic means concentric with said annular gap, a substantially seamless cup-shaped casing of non-magnetic material for said magnetic means, the peripheral edge of said casing being engaged with the outer surface of said annular plate member for substantially enclosing said magnetic means with the exception of the annular gap portion thereof, a head member having a sound chamber and a passage thereto, a diaphragm having a winding thereon adapted to be disposed in said annular gap, means for supporting said diaphragm in said head member in cooperative relation to said sound chamber, and means for mounting said head member in connection with said annular plate member with said winding centered in said annular gap, said head member being cooperative with said annular plate member and said casing for substantially wholly enclosing said magnetic means and said diaphragm.

2. In a sound transducer of the electrodynamic type employing a permanent magnet field structure, in combination, magnetic means for providing an annular gap having a high flux density, an annular plate member of non-magnetic material disposed on said magnetic means concentric with said annular gap, a substantially seamless cup-shaped casing of non-magnetic material for said magnetic means, the peripheral edge of said casing being engaged with the outer surface of said annular plate member for substantially enclosing said magnetic means with the exception of the annular gap portion thereof, a head member having a sound chamber and a passage thereto, means for mounting said head member in connection with said annular plate member for substantially wholly enclosing said magnetic means, a diaphragm having a winding thereof adapted to be disposed in said annular gap, and means including said head member for mounting said diaphragm in cooperative relation t'o'said sound chamber with said winding centered in said annular gap.

OSBORNE I. PRICE. 

